Circuit breaker



Sept. 29, 1953 B. G. TREMBLAY Erm.

CIRCUIT BREAKER 2 Sheets-Shree?I l Filed Feb. 1l, 1950 INVENTORS Bernard G.Tremb|oy ond WITNESSES:

William H.S|ue|len. 6C BY' 71/ ATT ORNEY Patented Sept. 29, 1953 CIRCUIT BREAKER Pittsburgh, and William Bernard G. Tremblay,

H. Stuellein,

East McKeesport, Pa., assgnors to Westinghouse Electric Corporation, East Pittsburgh,

Pa., a corporation of Pennsylvania Application February 11, 1950, Serial No. 143,722

8 Claims.

This invention relates to circuit breakers, and more particularly to circuit breakers of the type used to control light to moderate power distribution circuits.

Certain features disclosed but not claimed in this application are fully disclosed and claimed in copending application Serial No. 141,136, led January 28, 1950, by J. B. MacNeill, F. E. Florschutz, T. Lindstrom, and B. G. Tremblay, and assigned to the assignee of this application.

An object of the invention is to provide a circuit breaker embodying an improved electromagnetic trip device provided with a novel time delay device.

Another object of the invention is to provide a circuit breaker having an electromagnetic trip device of improved construction embodying an air dashpot and a, high-speed resetting valve to permit high-speed resetting of the trip device.

Another object of the invention is to provide a circuit breaker having an electromagnetic trip device and an improved time delay device of the air dashpot type embodying a high-speed reset valve which is operated directly by the electromagnet.

Another object of the invention is to provide a circuit breaker having an electromagnetic trip device including a trip rod and a time delay device of the air dashpot type with an improved high-speed reset valve operated directly by the trip rod.

The novel features that teristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is an elevational view, partly in section, of a circuit breaker embodying the principles of the invention;

Fig. 2 is a fragmentary elevational sectional view showing one of the control valves for the time delay device and the adjusting means therefor, and

Fig. 3 is a vertical sectional view through the trip device and the time delay device therefor.

Referring to Fig. 1 of the drawings, the circuit breaker includes a plurality of pole units each comprising a contact structure indicated generally at II, and an over-current trip device indicated generally at I3. The contact structure and the trip device for each pole unit are mountare considered characed on a separate insulating base I5 which is rigidly secured to a metal supporting panel I1. Since the pole units are alike, only the center pole unit is illustrated and described herein.

The contact structure II comprises stationary main and arcing contact I9 and 2| both secured on the inner end of a terminal conducting bar 23, and cooperating movable main and arcing contacts 25 and 21. The movable contacts are rigidly secured to a contact carrying member 29 pivotally mounted by means of a pivot pin 3| on a U-shaped switch arm 33 which, in turn, is pivotally supported by pivot means 35 on brackets 31 rigidly mounted on the insulating base I5.

The movable contact carrying member 29 is electrically connected by means of a flexible conductor 39 to the energizing coil of the trip device I3. A spring 4| compressed between the movable contact carrying member 29 below its pivot 3| and the insulating base I5 provides contact pressure in the closed position of the breaker and also biases the movable contact structure in opening direction.

The movable contact structure is normally maintained in the closed position by means of an operating mechanism indicated generally at 43 mounted in a U-shaped frame 45. The frame 45 is supported on a platform 41 which forms a cross member of a generally U-shaped main bracket comprising a pair of spaced side members 49 rigidly connected at theil` outer ends by the cross member or platform 41. The platform 41 extends substantially across the width of the breaker and the side members 49 are suitably secured to the metal panel I 1 on the outside of the two outer pole units of the breaker.

The operating mechanism includes a lever 5| mounted on a pivot pin 53 supported in the side members of the frame 45. The lever 5| carries a rod 55 extending across all of the poles of the breaker and is connected by means of insulating connecting members 51 to the pivot pins 3| in the free ends of the switch arms 33 for the several poles of the breaker so that upon operation of the rod 55 the movable contacts of all of the poles move in unison.

An operating linkage comprising toggle links 59. 6| and 63 is provided to releasably hold the lever 5| and consequently the movable contacts in the closed position and to operate the movable contacts to open and closed positions. The toggle link 59 is pivotally connected to the lever 5I by means of a pivot pin 65 and the toggle link 63 is pivoted on a fixed pivot 61 supported in the frame 45. The toggle link 6| is pivotally con- 3 nected to the links 59 and 63, respectively, by knee pivot pins 69 and 1 I.

The linkage 59, 6I, 63 comprises two toggles, one of which 59-6I may be designated as the tripping toggle and the other 5|-63 .as the closing toggle. The tripping toggle 59-6I is normally slightly underset above a line drawn through the centers of the pivot pins 55-1l and the closing toggle Kil-63 is normally underset below a line drawn through the centers of pivot pins 61-69. The closing toggle 6|-63 is normally prevented from collapsing downward by a support member 13 pivoted on a pivot pin 15 supported in the frame 45 and having ashouldered portion engaging under the knee pivot pin 1 I The tripping toggle 599| is normally biased in a direction to cause its collapse by a component of the force of the springs 4| which bias the movable contact structures for the three poles of the breaker in opening direction and bias the 'connecting members 51 toward the left (Fig. 1). The tripping toggle 59--6I is normally prevented from collapsing by means of a main latch member 11 pivoted on the pin 53 and connected by means of La link 19 to the knee pin 69 of the tripping toggle.

The main latch member 11 is held in latching position by an intermediate latch lever 8| pivoted on the pin 15. The intermediate latch lever carries at its upper end a latch roller 33 engaging the main latch 11 and at its lower end has a latching portion 85 normally engaging a latch member 91 on a channel-shaped latch 39 pivoted on a pivot pin 9| in the'frame 45. A spring 93 serves to bias the latch lever 8| and the latch 89 to their latching positions.

A trip bar 95, extending across all of the poles of the breaker, is rigidly mounted on the righthand end'of the channel-shaped latch 99 and has insulating brackets 91 (only one being shown) secured thereto, there being a bracket 91 for each pole of the breaker. Each of the brackets 91 has a headed screw 99 adjustably mounted thereon for cooperating with the trip device I3 of its associated pole in a manner to be presently described.

The breaker is tripped open manually by means of ya cam member |0I mounted on the inner end of a handle shaft |93 journaled in a bearing |05 mounted in the front piece of the frame 45. The handle is not shown in the drawings but is rigidly secured to the outer end of the shaft |03 and biased in both directions to a central position in a well known manner by means of a spring |01.

Rotation of the handler shaft |03 in tripping direction causes the cam member |0| to engage and actuate the latch member V89 in counterclockwise or unlatching direction to unlatch the intermediate latch lever 8|, which, in turn, releases the main latch 11. This permits the tripping toggle 59-6I to collapse upwardly to eiect opening of the breaker contacts, During Athe collapse of the tripping toggle a portion |09 of the toggle linkv 6| engages and actuates the support member 13 to a non-supporting position, thereby freeing the closing toggle .5I- 53. The closing toggle thereupon collapses downwardly and during its collapse resets and relatches the tripping toggle 59-6 I.

The breaker contacts may now be operated to the closed position by rotating the shaft |03 Aand the cam I9| in the direction opposite to the tripping direction. This causes the cam |0| to engage a projection I I on the closing toggle link 63 and moves this link counterclockwise about its pivot 61 until the support member 13 resumes its supporting position below the knee pivot pin 1 I. During the closing operation the link 19 prevents collapse of the tripping toggle 59-6I which acts as a thrust transmitting means and moves the movable contact structure to the closed position.

The breaker is yautomatically tripped open by operation of the trip device |3 for any pole of the breaker. The trip device includes generally a tripping electromagnet |13 (Figs. 1 and 3) and a time delay device ||5. The tripping magnet ||3 includes a C-shaped magnet yoke ||1. The ends |23 of the magnet yoke form mounting feet and are drilled and tapped to receive mounting bolts |25 and |21 as shown in Fig. 1.

The upper end of a stationary magnet core |29 is provided with an internal thread which cooperates with a threaded nipple |31 disposed in an opening in the magnet yoke to rigidly secure the stationary corev |29V to the magnet yoke. i

Surrounding the stationary core member |29 is an insulating tube |39 around which 'is disposed the energizing coil I4| of the magnet.

As shown in Fig. l, the bolt |25 which secures the upper end of the magnet yoke to the base I5 also secures the flexible Vconductor 39 to the upper turn of the coil |4I. The lower turn of the coil I4| is'formed into a lug |43 which, together with the inner end of a terminal |41 is secured t0 the base I5 by means of a'bolt |49. A tubular member |5| (Fig. 3) of magnetic material is mounted in an opening in the lower portion of the magnetic yoke I|1 and extends upwardly within the insulating tube |39. Disposed within the tubular member |5I is a movable core member or armature indicated generally at |53 comprising a cup-shaped upper portion |55 and a tubular lower portion |51 rigidly secured together by a suitable means such as brazing. The portion 155 is provided with a central opening through which extends a sleeve |59 surrounding -a trip rod |6| extending axially through the movable armature |53, the sleeve |59 and an opening in the nipple |31. A spring |63 Vcoiled about the trip rod |6| is compressed between a counterbore in the member |51 and the shouldered lower end of the sleeve |59. The upper end of the sleeve |59 is Vcounterbored and engages a spring clip |65 seated in an annular groove in the trip rod 16 I.

The trip rod |6I is moved upwardly to trip the breaker under vthe control of .the time delay device I5 which comprises, generally, a movable abutment or flexible diaphragm |61 (Fig. 3) cooperating with the lower end of the trip rod and several valve elements for admitting air to the space below the movable abutment or diaphragm at various rates to provide different amounts of time delay. The flexible diaphragm is disposed in a chamber formed in an upper housing member |1| and a lower housing 'member |13, both of said housing members being formed of molded insulating material. The outer edge of the diaphragm |61, together with a sealing gasket |15, is clamped between the housing members to form an airtight seal. The housing members |1 I-I13 are secured together and rigidly secured to the magnet yoke ||1 by means of bolts |11 (Fig. l) (only one of which is shown). rIhe central portion of the diaphragm |61 is clamped between upper' and lower clamp members |19 and |3|` respectively, the upper clamp |19 having an annular projection |83 extending downwardly through an opening in the lower clamp 1|8| and formed over against the lower face of the latter -to form an airtight seal.

Secured to the lower end of the trip rod |8| is a sleeve |85 provided with a ange |86 to the upper face of which is suitably attached a facing |88 of a tough resilient material, the flange |86 and facing |88 forming a valve member. The sleeve |85 is disposed in a central opening or passage |90 in the upper clamp member |19. An annular valve seat |92 formed on the clamp member |19 about the passage |90 is provided to cooperate with the facing |88 to close the passage |90 upon upward or tripping movement of the trip rod |6|. The lower portion |51 of the movable armature extends downwardly through an opening in the upper wall of the housing member |1| and is normally seated on the upper face of lthe upper clamp member |19 surrounding the opening |90. The lower end of the member |51 is counterbored and a coil spring |94 surrounding the sleeve |85 is compressed between the bottom of the counterbore and the upper face of the clamp member |19.

Since the spaces above and below the diaphragm |51 are completely sealed off from each other and the space above the diaphragm is at atmospheric pressure, any force 4tending to raise the trip rod |6| will be restrained by the partial vacuum below the diaphragm. In order to control the rate of tripping movement of the trip rod IGI, several valve devices are provided to admit air to the space below the diaphragm. The valve devices comprise a long-time delay valve indicated generally at |81 (Fig. 3), a short-time delay valve indicated generally at |89 (Fig. 2) and an instantaneous valve |9| (Fig. 3).

The long-time delay valve device |81 comprises a valve seat |93 molded integral with the bottom housing member |13, a tubular metal insert |95 molded in the housing member |13 surrounding the valve seat |93 `and having an internal thread therein, a valve member |91 cooperating with the valve seat 93 and threadedly engaging the tubular insert |95 whereby it may be adjusted and an insulating adjusting knob 99 supported on a flange 20| on the valve member |91. The air entering the space below the diaphragm is filtered by means of a suitable ltering material 203 supported between an annular ange 205 on the knob |99 and a cooperating annular projection 201 formed integral with the housing member |13. An air passage 209 in the form of a groove is provided along the threaded surface of the valve |91 and a passage 2|| is provided axially through the valve seat |93. The flow of air into the chamber below the diaphragm |61 is through the filter 203, the passage 209, the orice dened by the valve |91 and the valve seat |93 and through the passage 2||.

The knob |99 is provided with serrations (not shown) which engage corresponding serrations (also not shown) in the iiange 20| of the valve |91 so that rotation of the knob also rotates the valve to vary the oriice and thereby vary the amount of time delay. The valve device 81 is calibrated by pushing upward on the knob |99 to disengage it from the valve member |91. The knob is then set to zero, the valve member rotated to closed position and the knob released. The knob is restored to engagement with the valve by means of a spring 2|3 compressed between the bottom of the housing |13 and the knob.

The short-time delay valve |89 (Fig. 2) controls a passage for admitting air from the space above the diaphragm |61 to the space below the diaphragm at a rate to provide for tripping the breaker with a very short time delay in the order of alternating current cycles. The valve device |89 comprises a tubular valve member 2|5 (Fig. 2) disposed in an opening in the housing member 1| and having an enlarged head portion 2|1 seated in an opening in the housing member |13, the valve member 2|5 being held in position by a plug 2|9 screwed into the opening in the housing member |13. A valve 22| slidable in the tubular valve member 2| 5 normally cooperates with a valve seat formed in the tubular valve member to close a communication with opposite sides of the diaphragm. The valve element 2 I 5 is provided with an axial passage in which is disposed a tapered projection 223 of the valve 22| and which is normally closed by the valve 22|. The head 2|1 of the valve element 2|5 is provided with a. passage, and passages 225 and 221, respectively, in the housing members |1| and |13 communicate the space above the diaphragm to the area above the valve seat and the space below the diaphragm to the area below the valve seat.

Upward or opening movement of the valve 22| opens the passage through the valve element 2|5 and establishes communication from the upper to the lower side of the diaphragm. The valve 22| is actuated to the open position by means of a valve operating armature 229 which is biased by means of a spring 23| to its unattracted position and is attracted upwardly by the tripping magnet ||3. When this magnet is energized by overloads in the intermediate range of overloads of, for instance, 200% to 1000% of normal ratio current, the armature 229 is shown in Fig. 2 broken away, but is suitably pivotally mounted at its right hand end, The magnet yoke |1 has an opening 233 therein as shown in Fig. 2 to provide an air gap for operating the valve operating armature 229. A bracket 235 secured to the armature 229 engages under a head 231 on the valve 22| upon operation of the armature to actuate the valve to open position.

The rate of flow of air to the space below the diaphragm and consequently the rate of tripping movement of the trip rod |6| is controlled by the amount of opening of the valve 22|, The opening movement of the valve 22| is adjustably controlled by means of an adjustable S-shaped stop member 239 (Fig. 2). The upper portion 24| of the S-shaped member comprises an adjustable stop and is disposed in the path of the upturned end of the armature to be engaged thereby and thus limit the upward movement of the armature 229 and limit the extent of opening of the valve 22|. The center cross bar 243 of the S-shaped member has a threaded portion 245 of an adjusting screw 241, so that upon rotation of the screw 291 the S-shaped member 239 will be moved up or down, depending upon the direction of rotation, to provide for greater or lesser movement of the armature 229 and, hence, greater or lesser opening movement of the Valve 22|.

The lower end of the adjusting screw 241 has a reduced iiuted portion molded into an insulating knob 249. The knob 249 is rotatably mounted `in an insulating cross bar 25| secured to the underside of the housing member |13 by screws 253 only one of which is shown. A spring washer 255 seated in an annular groove in the adjusting screw 241 biases the screw upwardly and presses a flange on the knob 249 against the underside of the cross bar The adjusting screw 241 has an enlarged threaded portion 251 which passes through a clearance opening in the lower horizontal portion of the S-shaped member and threadedly engages a pointer 259. The lower vertical portion of the S-'shaped member has cut-away portions on opposite edges thereof which are engaged by projections on the pointer 259 so that the latter will travel upv and down without rotating. The outer end of the pointer 259 is reduced and extends through a Vertical slot in an index plate 26| supported at its lower end on the cross bar 25| and having its upper end secured to a cross member 263 molded integral with side members 265, which in turn, are integral with the housing member |1|.

The thread on the portion 251 of the adjusting screw has approximately twice the lead on the thread on the portion 245, hence, for one rotation of the adjusting screw the pointer 259 will move twice the distance as the S-shaped member 239. This makes possible an expanded dial on the index plate 26| and provides for more accurate setting of the short time delay device.

The instantaneous valve device |9| (Fig. 3)

is of the same construction as the short-time delay valve device with the exception that the tapered end which extends into the passage controlled thereby is omitted to permit instantaneous full opening of the passage permitting substantially unobstructed flow of air to the space below the diaphragm and instantaneous operation of the trip rod. Referring to Fig. 3, the instantaneous valve |9| is operated to the open position by means of an armature 261 similar to the armature 229 for the short time delay valve. The armature 261 is provided with projections 269 (only one being shown) which pivotally support the right hand end of the armature 261 in suitable recesses in the housing member |1|. The armature 261 is biased to unattracted position by means of a spring 21| and when operated, a bracket 213 secured to the armature engages a head 215 on the valve |9| and operates the valve to open position.

The main Vmovable core member |53 (Fig. 3) is biased to unattracted position by means of a pair of springs 211 (only one being shown) having one end attached to a member 219. One end of the member 219 is pivotally supported in notched studs 28| (only one being shown) and the other end of this member 219 is provided with inwardly extending projections 283 (only one being shown) which engage in an annular groove 285 in the tubular member |51 of the movable core. The other ends of the springs 21| are attached to a pointer 281 which is threadedly engaged by an adjusting screw 289 rotatably mounted in the cross member 25| and having an adjusting knob 29| secured to the lower end thereof below the cross member. The pointer 281 is provided with a reduced portion extending through a vertical slot in the index plate 26| to prevent rotation of the pointer when the adjusting screw is turned and to indicate the setting of the spring adjustment.

The springs 23| (Fig. 2) and 21| (Fig. 3) for the short time delay valve armature 229 and the instantaneous valve armature 261 are attached to pointers like the pointer 281 (Fig. 3) and are provided with adjusting screws and knobs like those associated with the main movable core member. B-y adjusting the tension of the springs 211, 23| and 21 the pick-up point or the amount of overload current required to operate the associated armatures may be varied. That is, the pick-up point for long time delay tripping, shorttime delay tripping and instantaneous tripping may be varied.

The trip device operates with time delays of diiierent durations in two distinct ranges of overcurrents below a predetermined magnitude, and instantaneously in response to overcurrents above the predetermined magnitude, or in response to short circuit currents. The ranges of overcurrents may be arbitrarily defined as, for example, a low range up to 500% or 600% of normal rated current, an intermediate range between 500% or 600% and 1000% of normal rated current, and instantaneous 1000% or more of normal rated current,

Assuming an overcurrent within the low range of overcurrents, the trip device will operate as follows: Upon the occurrence of an overcurrent in the low range the tripping electromagnet becomes energized and attracts the armature |53 upwardly. The armature acts through the spring |63 and the sleeve |59 to produce an upward thrust on the trip rod |6 I, the movement of the trip rod being retarded by the partial vacuum below the diaphragm |61. The initial upward movement of the trip rod |6| causes the valve facing |88 to engage the annular valve seat |92 on the clamp member |19 to thereby close the passage and completely seal off the spacesv above and below the diaphragm |61. On very low overload currents the pressure of the facing |83 onl the valve seat may not be sufficient to establish a perfect seal. It is for this reason that the spring |94 is provided. On such low overloads the spring |94 provides sucient pressure to effectively close the valve |88-|92.

The trip rod |6| moves slowly upwardly in tripping direction as air is drawn into the space below the diaphragm through the long time delay valve |81 until the upper end of the trip rod engages the headed screw 99 (Fig. 1) and actuates the latch mechanism to effect tripping of the breaker in the manner previously described. The time delay provided by the long time delay device |81 is in the order of seconds and may be varied by adjusting the valve |93|91 as set forth previously.

As soon as the breaker contacts are opened the tripping magnet ||3 is deenergized and the armature |53 and the trip rod are restored by the springs 211 and the force of gravity to their Fig. 3 position. Immediately upon deenergization of the tripping magnet H3, the armature |55|51 drops into engagement with the upper face of the clamp member |19. The lower end of the armature member |51 also engages the sleeve |35 and opens the valve la- |92 permitting equalization of air pressure above and below the diaphragm through the passage |90 and openings |96 in the lower end of |51 to thereby effect high-speed return of the parts of their normal lower positions as shown in Fig. 3.

When an overcurrent in the intermediate range of overcurrents occur, the electromagnet ||3 is energized suiciently to attract the short time delay armature 229 (Fig. 2) upwardly against the adjustable stop 24| opening the short time delay valve |89 an amount determined by the adjustment of the stop 24|. This admits 9 air to the space below the diaphragm |61 at a higher rate than the long time delay valve above and provides a relatively short time delay in the order of alternating current cycles in the tripping operation.

Energization of the tripping magnet I3 in response to an overcurrent in the intermediate range is not suiiicient to attract the armature 261 (Fig. 3) for the instantaneous valve |9|, however, upon the occurrence of an overcurrent of 1000% or more of rated current, both the short time delay armature 229 (Fig. 2) and the instantaneous armature 261 (Fig. 3) are attracted and open both the short time delay valve |89 (Fig. 2) and the instantaneous valve 9| (Fig. 3), thereby admitting air to the space below the diaphragm |61 at a rate suiiicient to permit substantially instantaneous tripping movement of the trip rod.

On short time delay and instantaneous tripping operations, the spring |63 limits the force applied by the moving armature |53 to the time delay device. On such operations the armature |53 is attracted immediately against the iixed core member |29 compressing the spring |63 which then supplies the force necessary to actuate the trip rod. Thus the pull exerted in the time ldelay device is limited to the maximum force exerted by the spring |63 when it is compressed. This prevents damage to the time delay device and also provides a uniform pull on the time delay device.

We claim as our invention:

1. In a circuit breaker, the combination of a trip device operable to effect automatic operation of said breaker comprising a trip member, electromagnetic means for operating said trip member, a time delay element having a passage therein for retarding tripping movement of said trip member, a chamber enclosing said time delay element, means defining a second passage communicating with said chamber on one side of said time delay element, valve means controlling said second passage to admit fluid to said chamber to retard tripping movement of said trip member, and a valve member on said trip member operable upon energization of said electromagnet to engage said time delay element to close the passage in said time delay element, said valve member being movable upon deenergization of said electromagnet to open said passage.

2. In a circuit breaker, the combination of a trip device operable to eiect automatic operation of said breaker comprising a trip rod, an electromagnet energized in response to overload currents for operating said trip rod, a time delay element having a passage therein for retarding tripping movement of said trip rod, a chamber enclosing said time delay element, means defining a second passage communicating with said chamber on one side of said time delay element, valve means controlling said second passage to admit iiuid to said chamber to retard tripping movement of said trip rod, said trip rod having a portion extending through said passage, a valve seat on said time delay element, and a valve member on said portion of said trip rod cooperating with said valve seat upon tripping movement of said trip rod to close the passage in said time delay element.

3. In a circuit breaker, the combination of an electromagnetic trip device operable to eiiect automatic opening of said breaker, said trip device comprising a trip rod, an energizing winding, an armature operable upon energization of said winding to actuate said trip rod, a timedelay element comprising a flexible diaphragm for retarding tripping movement of said trip rod, a member secured to said time delay element and having a passage therethrough, a chamber enclosing said exible diaphragm, means defining a second passage communicating with said chamber on one side of said iiexible diaphragm, valve means controlling said second passage to admit iiuid to said chamber on one side of said diaphragm to retard tripping movement of said trip rod, a valve seat on said member, and a valve member on said trip rod for engaging said Valve seat to seal the passage through said member upon tripping movement of said trip rod, and said armature upon deenergization of said winding engaging and moving said valve member to open said passage.

4. In a circuit breaker, the combination of a trip member movable to effect automatic operation of said breaker, a trip device comprising electroresponsive means operable when energized in response to overload currents to move said trip member, time delay means comprising a fluid dashpot, a movable abutment in said dashpot for retarding tripping movement of said trip member, said movable abutment having a control passage therein, an annular valve seat formed on said abutment, a valve member on said trip member movable into engagement with said valve seat upon tripping movement of said trip member to seal said control passage, means forming a second passage communicating with said dashpot on one side of said movable abutment and valve means controlling said second passage to admit fluid to said dashpot to permit retarded tripping movement of said trip member, said valve member being movable upon deenergization of said electroresponsive means to open said control passage and permit resetting movement of said trip member and said movable abutment.

5. In a circuit breaker, the combination of a trip rod movable to eiiect automatic operation of said breaker, electroresponsive means operable when energized in response to overload currents to eii'ect tripping movement of said trip rod, time delay means comprising a iiuid dashpot, a movable abutment disposed in said dashpot and provided with a control passage communicating the opposite sides of said abutment, said trip rod having a portion extending through said passage, a member fixed to said portion of said trip rod for engaging said abutment to close said control passage and to move said abutment upon tripping movement of said trip rod, means forming a second passage communicating with said dashpot on one side of said movable abutment and valve means controlling said second passage operable to admit iiuid to said dashpot at a predetermined rate to control the rate of tripping movement of said trip rod, said member moving to open said passage upon deenergization of said electroresponsive means to permit resetting of said abutment and said trip rod.

6. In a time delay device, a magnet, an armature mechanism actuated in one direction by attraction of the magnet, a normally open dashpot having a movable member connected to the armature mechanism, said dashpot being substantially closed during actuation of said armature mechanism by said magnet to retard movement of the mechanism in the direction in which it is actuated by the magnet, a valve communicating with the dashpot and normally open when Bisaccia Y ll the armature mechanism is in unattracted position, and a connection between the armature mechanism and the valve positively moving the valve to closed position at the beginning of the movement of the armature mechanism when attracted by the magnet.

7. In a time delay device, a movable element, a magnet, an armature actuated by the attraction of the magnet to move said movable element in one direction, a normally open dashpot having a movable member connected to the movable element, said dashpot being substantially closed during movement of said movable element by said armature when said armature is actuated by said magnet to retard movement of said movable element in the direction in which it is actuated by the magnet, a valve communicating with the dashpot and normally open when the armature is in unattracted position to permit exhaust of fluid from said dashpot, and a connection between the movable element and the valve positively moving the valve to closed position early in the movement of the armature when attracted by the magnet.

8. In a time delay device, an electromagnet, a mechanism actuated in one direction by energization of said electromagnet, a normally open dashpot having a movable member connected Y A 12 Y to said mechanism, said dashpot being substantially closed during actuation of said mechanism by said electromagnet to retard movement of the mechanism in the direction in which it is actuated by the electromagnet, a valve communieating with the dashpot and normally open in the deenergized condition of said electromagnet, and a connection between said mechanism and said valve positively moving said valve to closed position at the beginning of the actuation of said mechanism upon energization of said electromagnet.

BERNARD G. TREMBLAY. WILLIAM H. STUELLEIN.

References Cited in the file of this patent UNITED STATESVPATENTS 

